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resolver.py
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resolver.py
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# Copyright: 2006 Brian Harring <ferringb@gmail.com>
# License: GPL2
from pkgcore.restrictions import packages, values, boolean
from pkgcore.util.iterables import expandable_chain, caching_iter
from pkgcore.util.compatibility import all, any
from pkgcore.graph.choice_point import choice_point
from pkgcore.util.lists import iter_flatten
from pkgcore.graph.pigeonholes import PigeonHoledSlots
debug_whitelist = [None, "ref", "blockers"]
def debug(msg, id=None):
if id in debug_whitelist:
print "debug: %s" % msg
class NoSolution(Exception):
def __init__(self, atom, msg):
self.msg, self.atom = msg, atom
def __str__(self):
return "No Solution for %s: %s" % (self.atom, self.msg)
__repr__ = __str__
class resolver(object):
def __init__(self):
self.search_stacks = [[]]
self.grab_next_stack()
self.current_atom = None
self.false_atoms = set()
self.atoms = {}
self.slots = PigeonHoledSlots()
def add_root_atom(self, atom):
if atom in self.atoms:
# register a root level stack
self.ref_stack_for_atom(h, [atom])
else:
self.search_stacks.append([atom])
self.grab_next_stack()
def grab_next_stack(self):
self.current_stack = self.search_stacks[-1]
def iterate_unresolved_atoms(self):
while self.search_stacks:
assert self.current_stack is self.search_stacks[-1]
if not self.current_stack:
self.search_stacks.pop(-1)
if not self.search_stacks:
self.current_stack = None
return
self.grab_next_stack()
continue
try:
assert all(a in self.atoms for a in self.current_stack[:-1])
assert all(not x.blocks for x in self.current_stack)
except AssertionError:
import pdb;pdb.set_trace()
raise
debug("stack is %s" % self.current_stack)
a = self.current_stack[-1]
missing_atoms = False
if a not in self.atoms:
debug(" 1: missing atom: %s" % a)
missing_atoms = True
else:
c = self.atoms[a][0]
t = tuple(self.current_stack)
try:
c.depends + c.rdepends
except IndexError:
import pdb;pdb.set_trace()
raise
missing_atoms = False
for x in c.depends + c.rdepends:
# yes that was innefficient
if x not in self.atoms:
debug(" 2: missing_atom for %s: %s" % (a, x))
a = x
self.current_stack.append(x)
missing_atoms = True
break
else:
#ensure we're registered.
self.ref_stack_for_atom(x, t)
if missing_atoms:
# cycle protection.
self.current_atom = a
if a.blocks:
# import pdb;pdb.set_trace()
conflicts = self.slots.add_limiter(a)
if conflicts:
debug(" blocker %s would block previous choices of %s" % (a, conflicts))
cur = self.current_stack
self.atoms[a] = (choice_point(a, []), [t])
self.unsatisfiable_atom(a, "backtracking for blocker", False)
cur.pop(-1)
else:
debug(" blocker %s refed for %s" % (a, self.current_stack[-2]))
# ref it.
self.atoms[a] = [choice_point(a, []), []]
self.ref_stack_for_atom(a, t)
self.current_stack.pop(-1)
elif a in self.current_stack[:-1]:
# cycle ask the repo for a pkg configuration that breaks the cycle.
debug(" cycle detected for %s: stack %s" % (a, self.current_stack))
v = values.ContainmentMatch(a, negate=True)
yield packages.AndRestriction(a,
packages.PackageRestriction("depends", v), packages.PackageRestriction("rdepends", v))
else:
debug(" yielding %s for %s" % (a, self.current_stack))
yield a
else:
# all satisfied.
self.current_stack.pop(-1)
try:
assert not any(x.blocks for x in self.current_stack)
except AssertionError:
import pdb;pdb.set_trace()
raise
# sanity check. all nodes in the graph *should* have solutions.
# no exceptions, solutions are valid.
for c in (x[0] for x in self.atoms.itervalues()):
c.depends
c.rdepends
c.current_pkg
def satisfy_atom(self, atom, matches):
assert atom is self.current_stack[-1]
if not isinstance(matches, caching_iter):
matches = caching_iter(matches)
c = choice_point(atom, matches)
self.atoms[atom] = [c, []]
perm_unsatisfy = not bool(c)
while c:
p = c.current_pkg
conflicts = self.slots.fill_slotting(p)
if conflicts:
debug(" satisfy: atom %s pkg %s conflicts with %s" % (atom, p, conflicts))
c.force_next_pkg()
else:
debug(" results for %s was %s" % (atom, c))
break
# is this right?
self.ref_stack_for_atom(atom, self.current_stack)
if not c:
debug(" results for %s was empty through filtering/unification" % (atom))
cur = self.current_stack
self.unsatisfiable_atom(atom, permenant=perm_unsatisfy, indent=2)
if cur is self.current_stack:
self.current_stack.pop(-1)
else:
debug(" results for %s was %s" % (atom, c))
debug(" satisfy_atoms exiting: stack %s" % (self.search_stacks), "satisfy")
debug(" satisfy_atoms exiting: atoms %s" % str(self.atoms.keys()), "satisfy")
def unsatisfiable_atom(self, atom, msg="None supplied", permenant=True, indent=0):
# what's on the stack may be different from current_atom; union of atoms will do this fex.
assert atom is self.current_atom
a = self.current_atom
if permenant:
# register this as unsolvable
self.false_atoms.add(atom)
bail = None
istack = expandable_chain(self.atoms[atom][1])
for stack in istack:
if not stack:
# this is a root atom, eg externally supplied. Continue cleanup, but raise.
debug(" caught a root node, setting bail for %s" % (atom))
bail = NoSolution(atom, "root node was marked unsatisfiable, reason: %s" % msg)
# try:
# assert len(stack) > 1
# except AssertionError:
# import pdb;pdb.set_trace()
# raise
if not stack:
continue
elif len(stack) == 1:
c = self.atoms[stack[0]][0]
else:
try:
c = self.atoms[stack[-2]][0]
except Exception:
import pdb;pdb.set_trace()
try:
was_complete = self.choice_point_is_complete(c)
released_atoms, released_provides = c.reduce_atoms(stack[-1])
except IndexError:
was_complete = False
# bug
released_atoms, released_provides = (stack[-1],), []
t = tuple(stack[:-1])
debug(" released_atoms for %s == %s" % (stack, released_atoms), "unsatisfy")
for x in (x for x in released_atoms if x in self.atoms):
# how's this work for external specified root atoms?
# could save 'em also; need a queue with faster then O(N) lookup for it though.
print x
self.deref_stack_for_atom(x, t, indent=(indent+2))
if not c:
# notify the parents.
# this work properly? :)
istack.append([t])
elif was_complete and not self.choice_point_is_complete(c):
# if we've made it incomplete, well, time to go anew at it.
self.search_stacks.append(list(t))
self.grab_next_stack()
if bail is not None:
raise bail
debug(" exiting unsatisfiable: atoms %s" % self.atoms, "unsatisfy")
debug(" exiting unsatisfiable: stacks %s" % self.search_stacks, "unsatisfy")
def choice_point_is_complete(self, choice_point):
return all(x in self.atoms for x in choice_point.depends) and \
all(x in self.atoms for x in choice_point.rdepends)
def ref_stack_for_atom(self, atom, stack):
assert atom in self.atoms
if not isinstance(stack, tuple):
stack = tuple(stack)
if stack not in self.atoms[atom][1]:
self.atoms[atom][1].append(stack)
def deref_stack_for_atom(self, atom, stack, indent=0):
try:
assert atom in self.atoms
except AssertionError:
debug("%s atoms is %s, stack was %s" % (" "*indent, atom, stack))
raise
if not isinstance(stack, tuple):
stack = tuple(stack)
stack_l = len(stack)
l = [x for x in self.atoms[atom][1] if x[:stack_l] != stack]
if l:
self.atoms[atom][1] = l
debug("%s deref: atom %s, derefed stack %s" % (" "*indent, atom, stack), "ref")
else:
debug("%s deref: released %s" % (" "*indent, atom), "ref")
if atom.blocks:
self.slots.remove_slotting(atom)
del self.atoms[atom]